The use of a computer controlled machines to automatically machine parts has allowed the quick production of precise parts. For the specific case of machining parts, these machines are called computer numerically controlled (CNC) machines and are basically a computerized machinist that cuts material away from a block of material, e.g., metal or plastic, until the desired product is achieved. For example, a three-axis CNC milling machine has a cutting tool, an end mill, and allows for movement of the tool in three directions, X, Y, and Z. By moving the tool (or the part) and by spinning the end mill, material is removed from the block of material. The CNC machine has its own programming language which includes G and M codes.
In order to make programming a CNC machine more user friendly than writing many cryptic programming lines having G/M codes, a computer aided manufacturing (CAM) front end software tool is typically used. The CAM software tool has a graphical user interface (GUI) and may use a higher level language, such as Microsoft Visual Basic for Applications (VBA), the industry standard macro and scripting language, for programming. The CAM software then automatically generates the appropriate program, including the G/M codes, to run the CNC machine to manufacture the part. The CAM software tool is typically used by a manufacturing engineer.
FIG. 1 is a diagram of an exemplary process of manufacturing a part of the prior art. The manufacturer's process 110 begins in the design section 112 of a company where the part is designed on a computer aided design (CAD) system 114 by the design engineer. The CAD design is stored in a database (DB) 116. The CAD design represents the finished product and is “what” is manufactured. The CAD design, in the form of a geometric model or 2D/3D representation of the finished part, is then electronically transferred to the manufacturing section 120. The CAD model alone normally has insufficient information to manufacture the part, and the manufacturing engineer must add information, such as tool selection and machining parameters, into the CAM tool in order to specify “how” the part is to be machined. The CAM tool may display a solid or 3D surface model of the part, hence allowing the manufacturing engineer full visualization of the finished machined part. The CAM model is stored in DB 124. A program, for example, in VBA and Visual Basic (VB), is written by the manufacturing engineer in order to machine the part from a block of material. The CAM tool significantly reduces the complexity and time needed to write the VB/VBA program. When the programming is finished and debugged, the CAM tool automatically generates the CNC program. The CNC program, including the G-Code, is sent to the shop floor 130 to be executed on the CNC machine 132.
The manufacturing process of FIG. 1 has several problems. First, the process has a one-way flow of information, i.e., from design 112 to manufacture 120 to shop 130. For example, if the machinist on the shop floor needs to modify the CNC program to improve machining the part, this knowledge will normally not get back to either the manufacturing engineer or the design engineer. Similarly, any changes by the manufacturing engineer that could affect the design process are stored only in manufacturing DB 124. The design engineer typically has no access to DB 124, and even if the design engineer had access, the data representation of the CAD model in DB 116 is normally significantly different than the CAM model in DB 124. Thus lack of feedback information significantly impedes improvement of the overall machining process.
Another major problem is that if a feature or attribute in a part changes the manufacturing engineer needs to create another CNC program. VBA somewhat reduces this problem, by automating the programming of different versions of a standard part by using a macro. For example, a VBA macro can be written that characterizes a hole (a feature of a part), using attributes such as diameter, depth, XYZ location. The macro is complied and executed. The user is asked to enter values for the attributes or to make a selection among several predetermined choices. The macro takes these values, creates circles representing the holes, selects the cutting tools, automatically creates the drilling operations, and produces the G code program. The CNC machine inputs the G code program and machines the hole in the part. However, for example, if one feature is different in a similar part, e.g., a threaded hole rather than a counter bored hole, then a new VBA macro is typically written by the manufacturing engineer. Thus the conventional macro only increases program flexibility in a limited way by allowing different values for fixed attributes, but does not allow, for example, the addition/removal of features and attributes or the selection of a different manufacturing process.
In addition as the programmer is human, two programs, each written by a different person, but machining the same part, are probably different. This “personalized” methodology prevents the standardization of the part manufacturing process.
Therefore there is need for an improved process of machining a part were the design section, manufacturing section, and shop floor can exchange knowledge and were the programming methodology is more flexible, efficient and standardized.